President Trump's personal assistant, John McEntee, was sacked Monday, because he is now under investigation by the Department of Homeland Security for financial crimes, CBS News' Jacqueline Alemany confirmed Tuesday.

"The cause of the firing was an unspecified security issue", the Wall Street Journal reported, citing a White House official. In particular, WSJ indicated there was an issue with his security clearance.

White House spokeswoman Lindsay Walters declined to discuss the situation with the Journal, saying, "We do not comment on personnel matters".

McEntee, though, will continue to work for Trump.

"Mr. McEntee wasn't as well known as the others, but had been a constant presence at Mr. Trump's side for the past three years", the Journal reported. The almost five-minute video, which you can relive below, featured McEntee doing everything from throwing footballs into barrels and basketball hoops to opening doors with his throws.

Trump's 2020 Republican campaign announced Tuesday that he will serve as a senior adviser for campaign operations.

The former personal assistant was removed due to trouble with his security clearance and is now under investigation by the Department of Homeland Security for serious financial crimes, CNN reported Tuesday.

Trump reelection campaign manager Brad Parscale announced McEntee's hire alongside that of Katrina Pierson, a Trump campaign spokesperson in 2016 who will join the 2020 campaign as a senior adviser.